Apparatus and method for controlling sleep mode entry in broadband wireless communication system

Abstract

A sleep mode entry of a terminal in a broadband wireless communication system is provided. A base station includes an adjuster for, when a first terminal requests a sleep mode entry and lengths of requested sleep interval and listening interval do not meet a certain condition, adjusting the lengths of the sleep interval and the listening interval; and a determiner for setting a distribution of the sleep interval and the listening interval according to the adjustment of the adjuster and determining a sleep mode entry time of a second terminal which enters a sleep mode after the distribution of the sleep interval and the listening interval is set.

What is claimed is: 
     
       1. A base station in a wireless communication system, the base station comprising:
 an adjuster configured to, when a first terminal requests a sleep mode entry including lengths of requested sleep intervals and listening intervals that do not meet a certain condition, adjust the lengths of the sleep intervals and the listening intervals; and 
 a determiner configured to: 
 set a distribution of the sleep intervals and the listening intervals according to the adjusted lengths of the sleep intervals and the listening intervals; and 
 when a second terminal requests the sleep mode entry after the distribution of the sleep intervals and the listening intervals of the first terminal are set, determine a sleep interval among preset sleep intervals having the same length as an initial sleep interval length requested by the second terminal, and determine a sleep mode entry time of the second terminal in a start frame of the determined preset sleep interval, wherein the certain condition is defined according to a length of a sum of a maximum sleep interval and a maximum listening interval is greater than or equal to a length of the sum of remaining sleep intervals and listening interval frames. 
 
     
     
       2. The base station of  claim 1 , wherein the adjuster is further configured to adjust the lengths of the sleep intervals and the listening intervals to meet a condition expressed according to the following equation:
     S≧L ×( N− 1)
 
 
       where S denotes a number of initial sleep interval frames, N denotes an exponential component of a maximum sleep interval frame number, and L denotes a number of listening interval frames. 
     
     
       3. The base station of  claim 1 , wherein the adjuster is further configured to set the sleep interval length of the second terminal as an integral square multiple of two with respect to a preset minimum sleep interval length. 
     
     
       4. The base station of  claim 1 , wherein the preset sleep interval comprises sleep intervals for the first terminal. 
     
     
       5. The base station of  claim 4 , wherein the preset sleep interval further comprises sleep intervals set based on a plurality of criterion frames. 
     
     
       6. The base station of  claim 5 , wherein the determiner is configured to distribute the plurality of the criterion frames at regular frame intervals. 
     
     
       7. A method for controlling a sleep mode entry of a terminal at a base station in a wireless communication system, the method comprising:
 determining whether lengths of requested sleep intervals and listening intervals meet a condition when a first terminal requests the sleep mode entry; 
 adjusting the lengths of the sleep intervals and the listening intervals when the condition is not satisfied; 
 setting a distribution of the sleep intervals and the listening intervals according to the adjusted lengths of the sleep intervals and the listening intervals; and 
 when a second terminal requests the sleep mode entry after the distribution of the sleep intervals and the listening intervals of the first terminal are set, determining a sleep interval among preset sleep intervals having the same length as an initial sleep interval length requested by the second terminal, and determining a sleep mode entry time of the second terminal in a start frame of one of the determined sleep interval, wherein the certain condition is defined according to a length of a sum of a maximum sleep interval and a maximum listening interval is greater than or equal to a length of the sum of remaining sleep intervals and listening interval frames. 
 
     
     
       8. The method of  claim 7 , wherein the condition is expressed according to the following equation:
     S≧L ×( N− 1)
 
 
       where S denotes a number of initial sleep interval frames, N denotes an exponential component of a maximum sleep interval frame number, and L denotes a number of listening interval frames. 
     
     
       9. The method of  claim 7 , further comprising:
 setting the sleep interval length of the second terminal as an integral square multiple of two with respect to a preset minimum sleep interval length. 
 
     
     
       10. The method of  claim 7 , wherein the preset sleep interval comprises sleep intervals for the first terminal. 
     
     
       11. The method of  claim 10 , wherein the preset sleep interval further comprises sleep intervals set based on a plurality of criterion frames. 
     
     
       12. The method of  claim 11 , wherein the plurality of the criterion frames are distributed at regular frame intervals. 
     
     
       13. The method of  claim 7 , further comprising determining whether a maximum allocatable quantity of sleeping terminals are full, wherein the sleep mode entry time of the second terminal is determined when the maximum allocatable quantity of sleeping terminals are not full. 
     
     
       14. An apparatus of a base station for controlling a sleep mode entry of a terminal in a wireless communication system, the apparatus comprising:
 an adjuster configured to, when a first terminal requests a sleep mode entry including lengths of requested sleep intervals and listening intervals that do not meet a certain condition, adjust the lengths of the sleep intervals and the listening intervals; and 
 a determiner configured to:
 set a distribution of the sleep intervals and the listening intervals according to the adjusted lengths of the sleep intervals and the listening intervals; and 
 when a second terminal requests the sleep mode entry after the distribution of the sleep interval and the listening interval of the first terminal are set, determine a sleep interval among preset sleep intervals, having the same length as an initial sleep interval length requested by the second terminal, and determine a sleep mode entry time of the second terminal in a start frame of the determined preset sleep interval, wherein the certain condition is defined according to a length of sum of a maximum sleep interval and a maximum listening interval is greater than or equal to a length of the sum of remaining sleep intervals and listening interval frames. 
 
 
     
     
       15. The apparatus of  claim 14 , wherein the adjuster is further configured to adjust the lengths of the sleep intervals and the listening intervals to meet a condition expressed according to the following equation:
     S≧L ×( N− 1)
 
 
       where S denotes a number of initial sleep interval frames, N denotes an exponential component of a maximum sleep interval frame number, and L denotes a number of listening interval frames. 
     
     
       16. The apparatus of  claim 14 , wherein the adjuster is further configured to set the sleep interval length of the second terminal as an integral square multiple of two with respect to a preset minimum sleep interval length. 
     
     
       17. The apparatus of  claim 14 , wherein the preset sleep interval comprises sleep intervals for the first terminal. 
     
     
       18. The apparatus of  claim 16 , wherein the preset sleep interval further comprises sleep intervals set based on a plurality of criterion frames. 
     
     
       19. The apparatus of  claim 18 , wherein the plurality of the criterion frames are distributed at regular frame intervals. 
     
     
       20. The apparatus of  claim 14 , wherein the determiner is further configured to determine whether a maximum allocatable quantity of sleeping terminals are full, and determine the sleep mode entry time of the second terminal in response to determining that the maximum allocatable quantity of the sleeping terminals are not full.